Known approaches for protecting digital contents with DRM (Digital rights management) prevent unauthorized redistribution and restrict the ways a user can copy purchased content, thus limiting the piracy of commercially marketed digital material, which recently increased especially through the widespread use of peer-to-peer file exchange programs.
A known approach for protecting digital contents may be implemented by embedding a code in the digital content which prevents its copy to an unauthorized user device. Further protections may be provided, for example, by specifying a time period in which the content can be accessed or limiting the number of devices whereon the content can be installed or read. More particularly, a protected digital content and a code is transmitted from a client to a device of a user which purchases the content. The digital content is stored in the client or retrieved from the client in streaming from a network. When the user device receives the digital content in protected format, it decrypts such with the code.
A limitation of the above cited approach is that the client or content provided is responsible not only to deliver the digital content in protected format but also to implement the DRM, generating the code for the user device and storing it. In other words, the approach has a notable impact on the client. Moreover, this approach has a limitation of security because the code enabling the reading of the protected digital content is transmitted to the user device and is at least available to the user; in other words, the code is not consumed or destroyed after reading the protecting digital content in the user device and it remains available for the user.
It may be desired to reduce the impact of protecting digital contents on the client or content provider and to enforce the security of the DRM so that the code enabling the user device to read the digital content provider is not easily available at the user device side, thus overcoming the limitations of current approaches.
Different types of content services and common DRM problems in each type are discussed below.
In a rental service, the consumer purchases the right to use content for a fixed period of time. In a rental service like video on demand (VOD), the content lifetime is usually short (e.g. 24 hours) and the content is viewed on a single device. This may be the simplest type of service to implement in a consumer-friendly way.
In a subscription rental service, the consumer can access a substantial library of content. In a streaming video subscription service, for example, a subscriber may pay a monthly fee to access a variety of movies or TV programs. In a subscription rental service, consumers get access to content for a longer period of time so issues like the portability of the content (moving content between devices or accessing it multiple times on different devices), device upgrades and updates to the DRM technology may be considered. New licenses may be issued to subscribers to allow access for the next subscription period. This process should be as seamless as possible and not cause any disruption in accessing subscription content.
In a “purchase to own” model, the consumer purchases the right to consume the content for as long as desired. A common requirement in this type of service is the ability to backup content and licenses in case a device is damaged, stolen or upgraded. Upgrades of the DRM technology may also need to be handled so that new content can be purchased after the upgrade but previously purchased content can still be used. Consumers will often expect to access the content on multiple devices.
Some DRM content services only deliver content to one type of device. More commonly content distributors want to deliver content to a range of different devices, e.g. Android phones and iPhones. Multiple implementations of the same DRM technology are required for different devices and operating systems. The DRM client may be integrated with a media player, download manager, file system and other components on the device. As a result DRM clients are often installed on the device during manufacture or provisioning. A Microsoft Playready DRM client for example, may not be available on all the devices used by the content service's target consumers.
Also, many DRM technologies bind licenses to a particular device. This means that a new license must be issued to each device on which the consumer wants to play the content and it may be necessary to track the devices owned by a particular consumer.
Content can be downloaded or streamed. Streaming content is often only stored on the server side and not on the client device. This has the advantage that device upgrades or updates of the DRM technology are less problematic since older DRM content does not have to be ported to the new device or DRM version.
Examples of content services and the typical DRM problems associated with them are set forth below.
Video on demand includes a service type involving rental, e.g. 24-hour access to films and TV programs. Content delivery involves download or streaming, and devices include PCs or connected TVs. This type of service has few DRM usability issues as long as DRM clients are available for all target device types.
“Unlimited” video subscription service includes a service type involving subscription rental and streaming content delivery. Devices include PCs, connected TVs, tablets and mobile phones. Making DRM clients available for all target device types may require additional development. Subscription renewal should be as transparent as possible and the user should not encounter any interruptions in content access. Features like license predelivery and silent license delivery facilitate “invisible” subscription renewal.
Video download to own is a purchase-to-own service type with content delivery that is downloaded. Devices include PCs, connected TVs, tablets and mobile phones. Content and licenses should be backed up on the server-side to allow users to move them when devices are lost or upgraded. When updating the DRM technology, older content must still be playable. In major upgrades, a new version of previously purchased content may need to be delivered to subscribers.
As known, a method for playing digital contents protected by a DRM scheme provides that a user device plays the contents downloaded from a server provider only if a license is acquired and used to decrypt the content. The DRM (Digital Right Management) scheme may also require that the digital content is played with a specific player which is enabled to decrypt the digital contents download or received in streaming from the server. Also the streaming format from the server provider may be provided by the DRM scheme.
In this respect, the user device may store a native player which is different from the specific player requested by the DRM scheme. The term native player is referred to a player stored by a manufacturer of the user device together with the operating system; the native player may be faster than a “non-native” player, since it is more integrated with the operating system. For instance, the native player may use an accelerator of the operating system for improving the performance of rendering a movie.
Thus, if the specific player requested by the DRM scheme is not the native player of the user device, the performance of the digital content reproduction may be reduced.
In this respect, digital contents downloaded or streamed with the DRM PlayReady scheme of Microsoft, cannot be read and decrypted from the native player of an iPhone mobile user device, i.e. from Quick Time Player. In this case, a specific and non-native player must be downloaded into the iPhone mobile for decrypting and playing such contents. The non-native player inside the iPhone may perform less than the Quick Time Player, due to a slower communication with the operating system of the user device, i.e. iOS.
So a technical problem that may need to be addressed is how to play digital content protected with a DRM scheme without downloading a specific player, such specific player being however required by the DRM scheme to decrypt and play the digital content which is downloaded or streamed from the server provider. Another technical problem is how to provide a method for securely playing digital contents protected by a DRM scheme with a secure and improved performance and flexibility (e.g. without leaking out decryption keys and contents), especially for what concerns the phases for decrypting and playing the digital contents in the user device, thus overcoming the limitation which currently affects the prior art method.